Many navigation systems are available to help users navigate from one location to another. When using such systems, the destination is typically identified by GPS coordinates. However, most users do not think of locations in terms of GPS coordinates, so additional mechanisms are provided for designating destinations. For example, many systems provide a mechanism that allows users to identify a destination based on the name of the destination (e.g. “Sears”), the category to which the destination belongs (e.g. “Restaurants”), the street address of the destination, cross-streets near the destination, etc. When a user designates a destination in one of these manners, the navigation system typically performs a look-up operation to determine the GPS coordinates of the specified destination. Once the destination's GPS coordinates have been determined, the navigation system helps the user navigate to the destination.
Navigation systems may help users navigate to a selected destination in a variety of ways. One common way to help users navigate to a selected destination is to display a map of the user's current location, along with (a) an indication of the user's current position on the map, and (b) an indication of a route, from the user's current position, to the selected designation. The route indication may indicate the entire route, or a small portion of the route starting from the user's current position.
Typically, as the user moves, the display of a navigation system is updated to reflect the new position of the user relative to the displayed map. To avoid the user's position indicator from leaving the display, the display may be repeatedly updated with new map information. For example, as a user travels north, the displayed map may scroll down so that new map information is revealed at the top of the display, old map information scrolls off the bottom of the display, and the user's current position indicator remains approximately at the center of the display.
Such visual navigation aides are often accompanied by audible aides. For example, in addition to highlighting a suggested route on the displayed map, the navigation system may audibly tell the user when to turn, which direction to turn, the name of the street on which to turn, etc. Sophisticated navigation systems may also indicate things such as the user's speed, the current heading, the current weather at the destination, the current speed limit, traffic conditions along the proposed route, alternative routes, points of interest along the route, etc.
As long as navigation systems are able to receive accurate GPS signals, the systems work remarkably well in navigating users to the GPS coordinates associated with their designated destination. However, things start to break down in situations where GPS signals cannot be reliably received. Unfortunately, GPS signals can rarely be reliably received when something blocks the navigation system from the open sky. Navigation systems are blocked from the open sky in a variety of circumstances, including but not limited to dense tree cover, tall buildings, tunnels, covered parking structures, and most indoor environments.
Consequently, within navigation systems, most destinations are associated with GPS coordinates that are outdoors, even though the actual destinations are indoors. For example, the GPS coordinates for a store within a mall may actually correspond to location on the street in front of the mall. Similarly, the GPS coordinates for a covered parking structure may actually correspond to the street entrance to the parking structure, rather than any specific location within the parking structure.
Unfortunately, the outdoor GPS location associated with a destination is often not where the user actually needs to go. For example, a user that wants to visit a particular store in a mall may actually need to first find a parking spot in a covered parking structure near the mall, and then need to find the store within the mall itself. Conventional navigation systems may simply lead such a user to the outdoor GPS location associated with the mall, and then leave the user to fend for his/herself in finding a parking spot and the desired store. Often, the tasks of finding a suitable, available parking spot, and then the specific store in question, may involve a lot of wandering, frustration, and wasted time.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.